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PHP中的嵌套数据集结构

recurrence php-7 oop php

Mike Doe Backs · 技术社区 · 7 年前

我正在尝试实现一个面向对象的 nested dataset structure 在PHP中 another description of the structure )我已经创建了一个节点实现:

class Node
{
    private $parent;
    private $nodes = [];
    private $level = 1;
    private $left = 1;
    private $right = 2;

    /**
     * @return self|null
     */
    public function getParent()
    {
        return $this->parent;
    }

    private function setParent(self $parent = null)
    {
        $this->parent = $parent;
    }

    public function getLevel(): int
    {
        return $this->level;
    }

    private function setLevel(int $level)
    {
        $this->level = $level;
    }

    public function getLeft(): int
    {
        return $this->left;
    }

    private function setLeft(int $left)
    {
        $this->left = $left;
    }

    public function getRight(): int
    {
        return $this->right;
    }

    private function setRight(int $right)
    {
        $this->right = $right;
    }

    /**
     * @return static[]
     */
    public function getNodes(): array
    {
        return $this->nodes;
    }

    public function addNode(Node $new)
    {
        $new->setLevel($this->getLevel() + 1);
        $this->nodes[] = $new;

        // @todo
    }
}

然而 我需要帮助实施 这个 addNode 方法,该方法应向当前节点添加一个新节点并更新整个树,尤其是新添加的节点、父节点、子节点等。

为了使一切更简单,我创建了一个简单的测试用例,它将检查所有内容是否都正确实现:

$country = new Node();
$state = new Node();
$city = new Node();
$country->addNode($state);
$state->addNode($city);

assert($country->getLeft() === 1);
assert($country->getRight() === 6);
assert($country->getLevel() === 1);

assert($state->getLeft() === 2);
assert($state->getRight() === 5);
assert($state->getLevel() === 2);

assert($city->getLeft() === 3);
assert($city->getRight() === 4);
assert($city->getLevel() === 3);

2 回复 | 直到 7 年前

DarkMukke 7 年前

您不应该定义父对象,也不应该定义对它的引用,因为您可能最终进入引用循环,这在代码中不是一件坏事,但在设计中却可能导致代码在出错时无法理解。

至于 addNode 功能,你似乎走对了,

public function addNode(Node $new)
{
    //no need for getters and setters from inside the class
    $new->level = $this->level + 1;
    $this->nodes[] = $new;
    return $this;
}

我不知道你想干什么 left 和 right 不过。但我想它是最上层的家长是所有的路左边,最底层的孩子是所有的路右边。在这种情况下,我只是将它与级别区分开来。

我也不会使用private和use protected,我主要是在这里完成的,这样我就可以一路向前走,而不需要getter和setter来制作代码压缩程序,但是可以按照您的感觉来做:

class Node
{

    /**
     * @var static
     */
    protected $parent;
    /**
     * @var static[] 
     */
    protected $nodes = [];
    /**
     * @var int 
     */
    protected $level = 1;
    /**
     * @var int 
     */
    protected $left = 0;
    /**
     * @var int 
     */
    protected $right = 0;


    public function addNode(Node $new)
    {
        $new->level = $this->level + 1;
        $new->parent = $this;
        $new->left = $new->level - 1;
        if (empty($this->nodes)) {
            $this->right = 1;
        }
        $curr = $this;
        while (null !== $curr->parent) {
            //walking up to the current parent and telling it there is a new level added
            $curr->parent->right++;
            //setting the current level 1 up
            $curr = $curr->parent;
        }

        $this->nodes[] = $new;
        return $this;
    }
}

因为我回来了 $this ,我可以链接所有内容,或者像这样嵌套addnode调用

$country = new Node();
$state = new Node();
$city = new Node();
$country->addNode($state->addNode($city));

Mike Doe Backs 7 年前

休息了一天,喝了一杯咖啡,终于把这件事办好了。这并不像看起来那么简单,因为在添加新节点时必须重写整个树:

public function addChild(Node $new): void
{
    $this->nodes[] = $new;
    $new->setParent($this);
    $new->setLevel($this->getLevel() + 1);
    $new->setLeft($this->getLeft() + 1);
    $new->setRight($this->getLeft() + 2);

    $rootNode = $this;
    while (!empty($rootNode->getParent())) {
        $rootNode = $this->getParent();
    }

    $rootNode->setLeft(1);
    $this->updateTree($rootNode);
}

private function updateTree(Node $node): void
{
    $startIndex = $node->getLeft();
    foreach ($node->getChildren() as $child) {
        $child->setLeft(++$startIndex);
        $child->setRight(++$startIndex);

        if (count($child->getChildren())) {
            $this->updateTree($child);
            $startIndex = $this->getLastChild($child)->getRight();
        }
    }

    $node->setRight($this->getLastChild($node)->getRight() + 1);
}

private function getLastChild(Node $node): Node
{
    return $node->getChildren()[count($node->getChildren()) - 1];
}

这个类不久将在Github上发布。